Prostate cancer is the second leading cause of cancer related death among males. The Hispanic population is affected by the disease, and their five year survival rates are lower when compared to the white non Hispanic population although somewhat better than for the African-American males. Current tumor markers in use in the clinical setting have been shown to have low specificity and positive predictive value. Recently some studies have suggested distinct protein patterns expressed in the serum of Caucasian and African-American and Asian prostate cancer patients. No study has been done in a population with a strong Hispanic inheritance. The long term goal is to identify molecular markers related to prostate cancer (Pac) progression in Hispanics and to their response to therapy. The objective of this study is to evaluate protein patterns of Pac in a Hispanic population. The central hypothesis is that prostate gland proteome expression, changes through progression stages of the disease, therefore the onset of distinct proteomic patterns may serve as a predictor of tumor progression in the prostate gland and help to explain the characteristics of Pac In this population. The methodology will incorporate the use of Surface Enhanced Laser Desorption lonization (SELDI-TOF) and protein electro focusing to compare the patterns of protein expression in healthy patients and in newly diagnosed untreated prostate cancer patients. Our first specific aim is to identify a protein pattern in the sera of newly diagnosed Hispanic prostate cancer patients in Puerto Rico. Since signature protein(s) that appear in these Hispanic patients and that are absent or not described in other populations, may account for the difference PCA characteristics in this population, our second aim is to select and characterize distinct protein(s) that may be crucial to the understanding of the underlying molecular mechanisms and physiological significance. Finally our third aim is to correlate protein patterns with progression of the disease and type of treatment, in the context of this project, results from these correlations may serve as the base for a broader study to find predictive markers to assign patients to specific therapies. The rationale for this work is that the identification of early markers of disease and of markers for cancer stage progression will eventually translate into better diagnosis and survival rate for the Hispanic population and that these markers may acquire generalizability. With the capability of characterizing the protein(s) that composes the different profiles, it will be possible to study their possible role in the physiology of the disease. This knowledge will significantly enhance the capacity to target these proteins for the development of new therapies or a better use of current therapies, thus improving survival.